Panel interlocking means



March 3, 1970 J. H. LOCK 3,497,92

PANEL INTERLOCKING umns Filed 001;. 2, 1967 2 Sheets-Sheet 1 INVENTOK JOSEPH u. LOCK ATTOKN EY March 3, 1970 J. H. LOCK PANEL INTERLOCKING MEANS VI M Z M NO R .w EL Q 6 V "H m mu %A 2 m 5 0mm J 2 2 5 2 M Z w. a h I 0 o d L m M;

United States Patent 3,497,924 PANEL INTERLOCKING MEANS Joseph H. Lock, Mableton, Ga., assignor to The Mead Corporation, a corporation of Ohio Filed Oct. 2, 1967, Ser. No. 672,100 Int. Cl. B65d /10, 65/10 4 Claims ABSTRACT OF THE DISCLOSURE A six-sided container having bottom, side and end walls is provided with a pair of closure panels which, when interlocked, constitute a sixth side of the container. Web structure is provided at each of the four corners of the carton to aid in rendering the carton substantially dust H tight and a locking flap is foldably joined to an edge of each end panel and is provided with a locking aperture disposed in coincidental relationship with overlying locking tabs formed in the carton closure panels and by this means the interlocked locking flaps are held in closed position. The closure panels are interlocked according to the invention by means of locking tabs and slots provided respectively in the closure panels.

According to the invention a pair of panels are adjoined by a locking tab having a base portion and a transversely disposed shoulder portion formed on one panel and arranged to cooperate with a continuous slot having a locking part formed in the other panel and having an entry part formed in a guide panel foldably joined to an edge of the other panel. The transversely extending shoulder portion of the locking tab is arranged to engage the locking part of the continuous slot and the base portion of the locking tab is arranged to occupy the entry portion of the continuous slot, the engaging parts being diagonally disposed relative to the adjacent edges of the guide panel and the other panel which are defined by a fold line. According to a feature of the invention, the entry portion of the continuous slot is configured so as to provide a biasing edge which engages a part of the locking tab and which tends to cause the guide panel to occupy a position in the same plane as the panel to which it is foldably joined. Furthermore, the entry portion of the continuous slot defines in the guide panel a guide tab which aids in the formation of the lock by tending to position the locking tab correctly with respect to the continuous locking slot. According to another feature of the invention, a guide slot is formed in the panel from which the locking tab extends and is disposed adjacent the base portion thereof and opposite the transverse locking edge;

For a better understanding of the invention, reference may be had to the following detailed description taken in conjunction with the accompanying drawings in which FIG. 1 is a perspective view partially broken away to expose the interlocking means of this invention by which two panels are interlocked to form the bottom of the carton; FIG. 2 is a plan view of a blank from which the carton of FIG. 1 is formed; FIG. 3 is a view similar to FIG. 1 and which represents a modification of the invention and in which FIG. 4 is a plan view of the blank from which the carton of FIG. 3 is formed.

In the drawings, the numeral 1 designates a main panel of the carton which as depicted in FIG. 1 constitutes the top of the carton. A side wall is designated by the numeral 2 and such wall is foldably joined to a side edge of top panel 1 along fold line 3. Side wall 4 is similarly joined to the other side edge of top panel 1 along the fold line 5. The wall of the carton opposite from wall 1 is a composite structure comprising closure panel 6 which is foldably joined to side wall 2 along fold line 7 and a similar complementary closure panel 8 foldably joined to side wall 4 along fold line 9.

In order to draw the panels 6 and 8 into cooperative relationship with each other, suitable tightening apertures 10 and 11 are formed in panel 6 while similar tightening apertures 12 and 13 are formed in panel 8. As is well understood in the art, suitable machine elements are arranged to enter the tightening apertures 10 and 11 and move generally toward similar machine elements disposed within tightening apertures 12 and 13 which machine elements in turn cooperate to draw the panels 6 and 8 into the desired interlocking relationship so as to condition these panels for securement to each other according to this invention.

The ends of the carton are closed by suitable end panels 14 and 15 which are foldably joined respectively to the end edges of top panel 1 along fold lines 16 and 17. A locking flap 18 is foldably joined along fold line 19 to an edge of end panel 14 and is provided with a suitable locking aperture 20. In like fashion, a locking flap 21 is foldably joined along fold line 22 to the end panel 15 and a locking aperture 23 is formed therein. Suitable flexing lines 24, 25 and 26 are formed in end panel 14 and serve to facilitate manipulation of suitable locking tabs into the locking aperture 20. Similarly score lines 27, 28 and 29 are formed in end panel 15 and serve to facilitate the formation of a lock via a locking aperture 23.

The corners of the carton are closed by suitable web structure 30, 31, 32 and 33. These web structures are identical inconstruction and only one such structure will be described in detail. For example, web 30 comprises a corner panel in which a pair of score lines 34 and 35 are formed together with a web tab 36 which is foldably joined along fold line 37 to an end edge of panel 6 and along fold line 7 to web 30. When the carton is closed, web structure 30 collapses on the lines 34 and 35 and assumes a position inside the carton at the corner thereof and web tab 36 occupies a position immediately adjacent thereto and in face contacting relation with the end 38 of locking flap 18. Web structures 30-33 inclusive form no part of the present invention and a description thereof is included herein merely for the sake of completness.

According to this invention, a guide panel 39 is foldably joined along fold line 40 to an edge of panel 6 and a plurality or diagonal continuous substantially zig-zag slots 41-44 inclusive are disposed astride the edges of panel 6 and of guide panel 39 defined by weakened fold line 40. These slots 41-44 are arranged to receive a plurality of locking tabs 45-48 respectively which are formed on panel 8.

In order to properly align the panels 6 and 8 during the performance of an interlocking operation, a positioning tab 49 is formed on an edge of panel 8 and a cooperating positioning slot 50 is formed in guide panel 39. Since the positioning tab 49 is arranged with a rounded nose portion 51, suitable guiding action is achieved to effect proper orientation of the locking tabe 45-48 inclusive with respect to their associated continuous slots 41-44.

Since the locking tabs 45-48 are identical, only one such tab 48 is described in detail. Tab 48 is provided with a transversely extending shoulder which defines a locking edge 52 which edge is angularly or diagonally disposed with respect to the general disposition of edge 53 of panel 8. Furthermore, locking tab 48 is constructed with a base portion designated by the letter X.

All the continuous slots 41-44 are of identical construction and only one slot 44 is described in detail. Slot 44 is provided with a locking part 54 which constitutes that portion of the slit which is formed in panel 6 together with an entry part designated by the letter Y and which is formed in its entirety in the guide panel 39.

In order to form an interlocking relationship between locking tab 48 and continuous slot 44, it is simply necessary to fold the guide panel 39 out of the plane of panel 5 and then to insert the locking tab 48 into the continuous slot 44. When the tab reaches its locking position, the locking edge 52 thereof occupies a position of abutting relationship to the locking part 54 of continuous slot 44 and the base portion X of locking tab 48 occupies the entry portion Y of the continuous slot 44.

The guide panel 39 is biased toward a position in the same plane as its associated panel 6 by virtue of the fact :hat the entry part Y of the continuous slot 44 is provided With a biasing edge designated by Z in FIG. 2. Thus the solid portion of guide panel 39 between the lower end of :he biasing edge Z and the fold line 40 simply results in a force exerted by the flat plane of locking tab 48 which tends to urge guide panel 39 into a position of substantially coplanar relationship with panel 6. This solid portion of guide panel 39 is designated in the drawings by the numeral 55 and is arranged to ride into the guide slot 55a formed adjacent the base portion X of locking tab 48.

From the description above, it is apparent that an essential feature of the invention constitutes the angular disposition of the locking part 54 of the slot 44 relative to the fold line 40 as well as the corresponding angular disposi tion of the locking edge 52 of locking tab 48. Furthermore, it is apparent particularly from FIG. 2 that the biasing edge Z of the continuous slot 44 is off-set in the direction of panel 6 from the remaining entry portion of the continuous slot 44 which portion is formed entirely within the guide panel 39. The part of the continuous slot 44 which is interposed between the locking part 54 thereof and the biasing part Z thereof defines a guide tab which in reality is struck from the guide panel 39 and disposed in the plane of and forms a part of panel 6. Thus when guide panel 39 is folded out of the planev of panel 6, the guide tab disposed between the locking part 54 and the biasing edge Z of slot 44 cooperates with the guide panel 39 properly to position the locking tab 48 as it enters the continuous slot 44.

The cooperation of locking tabs 45-47 with the slots 4143 respectively is identical to that described in connection with locking tab 48 and continuous slot 44 and a detailed description of the locking action of these parts is not deemed necessary.

One valuable feature of the interlocking means formed according to this invention resides in the fact that the panels 6 and 8 can readily be unlocked in zipper-like fashion. For example, in order to open the carton as viewed for example in FIG. 1, it is simply necessary to grasp the end edge of panel 8 in the region designated by the arrow 56 and to exert a downward force thereon. This action causes the locks 48, 47, 46 and 45 to disengage their corresponding continuous slots 44, 43, 42 and 41 in a zipper-like fashion.

In order to enhance the security of the interlocking means, it is desirable but not necessary to provide locking elements 57 and 58 in the panels 6 and -8 and to drive these two locking elements into the locking aperture 23 as the carton is completed. Similarly, it may be desirable but not necessary to provide locking elements 59 and 60 in the panels 6 and 8 and to drive these elements into the locking aperture 20 as the formation of the carton is completed.

It is apparent particularly from FIG. 2 that the panels 6 and 8 are of a generally trapezoidal configuration. Of course the angular disposition of the locking edges such as 52 and the associated locking part 54 of the continuous slot 44.is thus logically accommodated.

It is not necessary however to use the invention only in conjunction with trapezoidal panels. For example and with reference to the modification of this invention asshown in FIGS. 3 and-4, the panels 6 and 8 may be rectangular and the angular disposition achieved by simply reorienting the parts such as 52 and 54 as is shown in FIG. 4. The carton depicted in FIGS. 3 and 4 is otherwise identical to that depicted in FIGS. 1 and 2 and the same numerals have been used in both modifications. The shape of the panels 6 and 8 and the spacing between adjacent locking tabs and slits constitute the significant differences between those two modifications together with the reorientation of the critical angles of edges 52 and of locking parts 54 and of parts associated therewith. Since the locking tabs and slits are more closely spaced in the arrangement of FIGS. 3 and 4, additional identical locking tabs 48a and 48b and slits 44a and 44b are shown in FIGS. 3 and 4.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An arrangement for interlocking a pair of panels, said arrangement comprising a guide panel foldably joined along one edge thereof to one edge of one of said panels along a weakened fold line, a locking tab formed on an edge of the other of said panels and disposed thereon in outwardly protruding relation, said locking tab having a base portion and a generally transverse shoulder portion defining a locking edge disposed diagonally with respect to the general disposition of said edge of said other panel, and a continuous substantially zig-zag shaped slot disposed astride said weakened fold line and having an end portion of said slot defining a locking part formed in said one panel, and the remaining portion of said slot crossing said fold line and defining an entry part formed in said guide panel, said locking part of said slot being diagonally disposed relative to said weakened fold line and at an angle corresponding to the angular disposition of said locking edge relative to said edge of said other panel, said locking part of said locking slot being disposed in parallel abutting relation to said locking edge of said locking tab and said entry part of said slot being adapted to receive said base portion of said locking tab.

2. An arrangement according to claim 1 wherein said entry part of said slot is configured to define a biasing edge in said guide panel which is offset from the remaining portion of said entry part of said slot in the general direction of said one panel and which is engageable with said locking tab so as to bias said guide panel toward a position of substantially parallel generally coplanar relation relative to said one panel thereby to secure said panels together.

3. An arrangement according to claim 1 wherein a guide slot is formed in said other panel adjacent the base portion of said locking tab and in generally normal relation to said locking edge of said locking tab and on the opposite side thereof from said shoulder portion, said guide slot being disposed to receive a part of said guide panel adjacent one end of said entry part of said slot.

4. An arrangement according to claim 9 wherein said biasing edge is diagonally disposed at an angle to the adjacent edges of said guide panel and said one panel defined by said fold line which angle corresponds to the angular disposition between said locking part of said slot and said adjacent edges of said guide panel and said one panel.

References Cited UNITED STATES PATENTS 2,004,098 6/ 1935 Andrews. 2,956,720 10/ 1960 Rindal 22939 3,081,017 3/1963 Gerbino 22939 3,127,090 3/1964 Scott 22939 X BERNARD A. GELAK, Primary Examiner US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,497,924 March 3, 1970 Joseph H. Lock It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, line 54, claim referencenumeral "9" should read Signed and sealed this 1st day of December 1970.

(SEAL)- Attest:

Edward M. Fletcher, It.

Attesting Officer Commisioner of Patents WILLIAM E. SCHUYLER, JR. 

